Aminocaproic Acid: Bleeding Control, Dosing, and Side Effects
Last updated September 7, 2026.
**Aminocaproic acid is an antifibrinolytic medicine, sold as Amicar, that is used to control bleeding when the body is breaking down clots faster than it can form them.** It works by blocking plasminogen and plasmin, the enzymes that dissolve fibrin, so clots that have already formed stay in place long enough for bleeding to stop. Because it holds clots together, it is not used when there is active clotting inside the blood vessels, and it must not be used for bleeding coming from the kidneys or upper urinary tract unless a specialist decides the benefit is worth the risk of a clot blocking the ureter. Tell your clinician right away about new muscle pain or weakness, since that can be an early sign of muscle injury from this drug.
What does it treat?
Aminocaproic acid is approved to treat excessive bleeding from systemic hyperfibrinolysis and from urinary fibrinolysis. In practice that covers bleeding after heart surgery involving cardiopulmonary bypass, bleeding in people with blood disorders such as aplastic anemia, bleeding tied to liver cirrhosis, abruptio placentae, and bleeding seen with some cancers, including cancer of the prostate, lung, stomach, and cervix. It is also used after prostate or kidney surgery and after severe trauma or shock when clots in the urinary tract are dissolving too quickly. Clinicians commonly prescribe it off label as a mouth rinse or oral dose to stop bleeding after dental extractions in people with hemophilia or von Willebrand disease, and for heavy nosebleeds or heavy menstrual bleeding when clot breakdown is the driver. It comes as a single ingredient product only, so there are no combination pills to watch for, though it is often given alongside clotting factor products or desmopressin.
How do you take it?
Aminocaproic acid comes as 500 mg and 1000 mg tablets, a 250 mg/mL oral solution, and an intravenous solution given in the hospital. For an acute bleeding episode, the label directs an adult loading dose of 5 g by mouth during the first hour, which is ten 500 mg tablets, five 1000 mg tablets, or 4 teaspoonfuls of the oral solution, followed by about 1 g per hour, which is two 500 mg tablets or 1 teaspoonful of solution at 1.25 g, continued for roughly 8 hours or until the bleeding is controlled. Do not exceed 30 g in 24 hours. You can take it with or without food, and taking it with a snack or a full glass of water helps if it upsets your stomach. If you miss an hourly dose, take it as soon as you remember, then go back to your schedule, and never take two doses at once to catch up. If you have reduced kidney function, your dose will be lowered, so make sure whoever prescribes it knows your kidney numbers. Stop the medicine and call your doctor if bleeding does not slow within the expected window, if you develop muscle pain or weakness, or if your urine turns dark or reddish brown.
Side effects to know
- Common: Common effects include nausea, vomiting, diarrhea, stomach cramps, headache, dizziness, feeling tired or generally unwell, stuffy nose, red or watery eyes, ringing in the ears, and a mild rash.
- Serious: Stop the drug and get medical help right away for muscle pain, tenderness, or weakness along with dark or cola colored urine, which can mean muscle breakdown and kidney injury, or for signs of a clot such as swelling and pain in one leg, chest pain, sudden shortness of breath, weakness on one side of the body, or trouble speaking. Seizures, a sharp drop in blood pressure with a slow heartbeat during an intravenous dose, sudden unexplained bruising or infection from a drop in white cells, and allergic reactions with hives, facial swelling, or wheezing also need immediate care.
Who should not take it?
Do not take aminocaproic acid if you have evidence of active clotting inside your blood vessels, including disseminated intravascular coagulation, unless heparin is being given at the same time under specialist supervision. It should not be used for bleeding from the upper urinary tract, because a clot can block a ureter or the kidney itself. Talk with your doctor first if you have had a deep vein clot, pulmonary embolism, heart attack, or stroke, if you have heart, liver, or kidney disease, or if you have had a recent blockage in an artery. Combining it with estrogen containing birth control pills or hormone therapy, with factor IX complex concentrates, or with anti inhibitor coagulant complexes raises the chance of a clot, so those combinations need a prescriber to weigh the risk. There are no adequate and well controlled studies in pregnant women, so it is used in pregnancy only when clearly needed, and it is not known whether it passes into human milk, so tell your clinician if you are breastfeeding. Alcohol does not have a listed interaction with this drug, but heavy drinking makes bleeding and liver problems worse, so keep intake low while you are being treated for active bleeding.
When is it an emergency?
Call 911 now if you collapse, cannot catch your breath, have chest pain, have sudden weakness or numbness on one side, cannot speak clearly, have a seizure, or have swelling of the lips, tongue, or throat with hives or wheezing. Painful swelling in one calf or thigh, or coughing up blood with breathlessness, needs emergency evaluation for a clot rather than a wait and see approach. New muscle pain or weakness with dark brown or cola colored urine, or passing much less urine than usual, needs same day emergency care. If too much is taken, or a child swallows any, call Poison Control at 1-800-222-1222 right away, and call 911 if the person is unconscious, seizing, or having trouble breathing.
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Common questions
What is the maximum dose of aminocaproic acid in a day?
The label ceiling is 30 g in 24 hours for adults. A typical acute bleeding regimen is 5 g by mouth in the first hour, then about 1 g per hour for roughly 8 hours or until bleeding stops, which comes to around 13 g in a day and stays well under the ceiling. Higher totals do not stop bleeding faster and raise the chance of muscle injury and clots. If you have reduced kidney function, your prescriber will use a lower dose than the standard one, because the drug is cleared by the kidneys.
Can I drink alcohol while taking aminocaproic acid?
The label does not list an interaction between aminocaproic acid and alcohol. The practical problem is that alcohol thins out clotting in its own way, irritates the stomach lining, and can restart bleeding from a dental socket, an ulcer, or the nose. Alcohol also adds dizziness on top of the dizziness this drug can cause. While you are actively being treated for bleeding, skip alcohol until the bleeding has stopped and your prescriber says you are done with the course.
Is aminocaproic acid safe in pregnancy or while breastfeeding?
There are no adequate and well controlled studies of aminocaproic acid in pregnant women, so the FDA labeling says it should be used during pregnancy only if clearly needed. It is sometimes used in obstetric bleeding, including bleeding from abruptio placentae, when the bleeding itself is the bigger threat. It is not known whether the drug passes into human milk, and the label advises caution when giving it to a nursing mother. Tell your obstetrician or hematologist if you are pregnant, trying to conceive, or breastfeeding, so they can weigh the bleeding risk against the unknowns.
Should I take it with food?
You can take aminocaproic acid with or without food. Nausea, vomiting, diarrhea, and stomach cramps are among the most common effects, so taking each dose with a light snack and a full glass of water often makes it easier to tolerate. Food does not meaningfully change how much drug reaches your blood. If the oral solution keeps coming back up, tell your prescriber, because the intravenous form may be needed instead.
What are the signs of taking too much?
Overdose signs include severe muscle pain and weakness, dark or cola colored urine from muscle breakdown, passing little or no urine, confusion, and signs of a clot such as a swollen painful leg, chest pain, or sudden shortness of breath. Seizures and a slow heartbeat with low blood pressure have also been reported. Call Poison Control at 1-800-222-1222 for a suspected overdose, or 911 if the person collapses, has a seizure, or is struggling to breathe. Bring the bottle or the tablet count with you so the team knows exactly how much was taken.
What medicines interact with aminocaproic acid?
Estrogen containing birth control pills and hormone therapy add to the clotting effect and increase the chance of a blood clot when combined with this drug. Factor IX complex concentrates and anti inhibitor coagulant complexes carry the same concern and are only combined with aminocaproic acid under specialist supervision. Tranexamic acid works the same way, so the two are not taken together. Give your prescriber a full list of what you take, including blood thinners, hormone products, and anything from a hematology clinic, before your first dose.